Purpose :
Posterior capsule opacification (PCO) occurs in some patients following cataract surgery. As part of the disease process, myofibroblasts contract and produce wrinkles in the lens capsule that affect visual acuity. Myofibroblasts in the lens arise from Myo/Nog cells that express the skeletal muscle specific MyoD transcription factor and the bone morphogenetic protein inhibitor noggin. In human anterior lens tissue removed during cataract surgery, Myo/Nog cells synthesize sarcomeric proteins and surround wounds in the epithelium. The goals of this experiment were to establish long-term cultures of human anterior lens tissue, characterize the Myo/Nog cell population and determine whether a novel drug that targets Myo/Nog cells eliminates myofibroblasts.

Methods :
Human anterior lens tissue obtained by capsulorhexis was cultured in serum free medium for 30 days. Explants were incubated for 24 hours with the G8 antibody complexed to DNA nanocarriers intercalated with Doxorubicin (G8:3DNA:Dox), to specifically target Myo/Nog cells. Some cultures were wounded on day 29. Tissue was analyzed for the presence of Myo/Nog cells and myofibroblasts by immunofluorescence localization of G8, noggin, MyoD, sarcomeric myosin and alpha smooth muscle actin (SMA) on day 30.

Results :
Myo/Nog cells labeled with G8 and noggin constituted approximately 6% of the cells in 30-day lens explants. Most, but not all G8 and noggin-positive (+) cells had synthesized MyoD, myosin and SMA. Myo/Nog cells that had synthesized skeletal muscle proteins were present in clusters or around wounds in the epithelium. The number of Myo/Nog cells increased following wounding of the epithelium. Treatment of lens explants with G8:3DNA:Dox eliminated the populations of G8+ and SMA+ cells in wounded and non-wounded lens tissue.

Conclusions :
Lens tissue remains viable in serum free medium for 30 days. While most Myo/Nog cells express markers of skeletal muscle differentiation, a subpopulation remains as myogenic progenitor cells. Myo/Nog cells produce myofibroblasts when challenged by tissue wounding late in culture. Myofibroblasts do not emerge following depletion of G8+ cells, thereby confirming that Myo/Nog cells are the source of myogenic cells in human lens tissue. These long-term, serum free cultures of human lens tissue have broad application for screening drugs with the potential to inhibit PCO.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.